Periodontal disease afflicts over an estimated 90 percent of the world's population. Lassari, E.P., Dental Biochemistry, 191-3, (1976). Although this disease is not life threatening, it often results in serious discomfort and tooth loss. The basic cause of this disease is bacteriological in nature. Both topical and systemic bactericidal agents have been found effective in combating the disease. Biological Basis of Periodontal Maintenance Therapy, G.C. Armitage, Proxis Publishing Company, 1980, pages 34-78.
Recently, it has been demonstrated that combinations of various salts and hydrogen peroxide solution, when properly applied as part of a treatment under the supervision of a dentist, are effective in controlling periodontitis. B.G. Rosling et al, Journal of Clinical Periodontology, Vol. 10 pp 487-514, 1983. Sodium bicarbonate, a particularly convenient and palatable non-toxic salt, is believed to be effective in this treatment. Keyes P.H. et al, Quintessence International No. 1, January 1978, Report 1590, pages 51-56 and No. 2 February 1978, pages 69-75.
The bacteria causing periodontal disease are anaerobic. Armitage, G.C., Biological Basis of Periodontal Maintenance Therapy, 1980. By providing high levels of oxygen, hydrogen peroxide is believed to be effective in killing these bacterial organisms. Hydrogen peroxide is the preferred oxidizing agent as it is readily available, proven effective and non-toxic.
In addition to treating periodontal disease, many individuals like to use baking soda and peroxide to clean their teeth. Several of the benefits cited by those using this combination include ability to remove stains, a clean feeling in the mouth, less mouth odor, and healthy gums.
A mixture of an approximately 60 percent sodium bicarbonate paste with a 3 percent solution of hydrogen peroxide has been used to treat periodontal disease. This method requires the user, immediately before use, to prepare the mixture in the palm of the hand. The mixture is then applied along the gum line. Due to the foaming action of the hydrogen peroxide, and because the mixture is prepared on the palm of the hand, this procedure is messy.
To overcome the inconvenience of the above procedure, various dentifrices have been formulated which contain oxidizing agents such as sodium perborate (Cella, et al., U.S. Pat. No. 3,885,028 and Molnar, U.S. Pat. No. 2,275,979), potassium chlorate, urea peroxide (Gordon, U.S. Pat. No. 4,522,805 and Schaeffer, U.S. Pat. No. 4,528,180) and magnesium peroxide. Balsam, M.S. et al, Cosmetics: Science and Technology, Volume 1, Second Edition, Wiley Interscience (1972) page 496.
Sodium perborate and potassium chlorate do not release significant levels of hydrogen peroxide in water. Kirk-Othmer Encyclopedia of Chemical Technology, Third Edition, Volume 17, page 1-22; Kern, D.M., J. Am. Chem. Soc. 77 5458, 1955. Although sodium perborate has been classified category 1 (Federal Register, Oct. 7, 1982) for temporary use as an oral wound cleaner, it is of questionable safety for frequent topical use on the mucous membranes of the mouth and throat because it contains boron which can undergo systemic absorption. (Federal Register Vol. 44 No. 214 page 63282, Friday, Nov. 2, 1979, Proposed Rules). Sodium perborate also has an undesirably low solubility in water of about 2.5%. This low solubility limits the concentration of oxidizing agent. Magnesium peroxide, an essentially insoluble salt in water, is similarly undesirable. Handbook of Chemistry and Physics, 59th Edition, 1978-79.
Various peroxide-releasing dentifrice formulations utilize urea peroxide as the oxidizing agent. However, urea peroxide in combination with sodium bicarbonate is not stable. As a result, preparations have been proposed in which the urea peroxide and sodium bicarbonate components are in separate compartments of a container (see Schaeffer, U.S. Pat. No. 4,528,180, column 2, lines 4-9).
Other sodium bicarbonate-containing, peroxide-releasing dentifrices may incorporate enzymes for generating hydrogen peroxide in situ. (See Kessler et al., U.S. Pat. No. 4,476,108 and Pellico et al., U.S. Pat. No. 4,537,764). However, the formation of hydrogen peroxide by enzymes is so slow that only low levels of peroxide are produced during brushing with these dentifrices.
Alkali and alkaline earth metal percarbonates, e.g., ammonium percarbonate, were also described as peroxide-releasing reagents for dentifrices more than eighty years ago. (Gane, U.S. Pat. No. 802,099 granted Oct. 17, 1905.) The percarbonates have not been actually used in dentifrice formulations, however, because of their high pH in solution which could cause severe irritation of the gums. Dentifrices containing such a percarbonate and an alkali metal bicarbonate have not been previously described or used.
It is among the objects of the present invention to provide a stable, peroxide-releasing tooth powder. It is a further object of the invention to provide such a formulation which is useful in the treatment of periodontal disease and which minimizes dental caries, in a safe, more convenient and more palatable form than embodied in any prior art formulation of which we are aware.